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API · /gearratio-api

Gear Ratio API

healthy 3,511 Subscribers

Gear-train ratio, speed and torque maths as an API, computed locally and deterministically. The ratio endpoint computes the gear ratio of a single pair from the driver and driven tooth counts (or pitch diameters), ratio = N_driven/N_driver, classifies it as a reduction (more torque, less speed) or an overdrive, and — given an input speed and torque — returns the output speed (input/ratio) and the output torque (input·ratio·efficiency). The train endpoint computes a compound gear train: the overall ratio is the product of the individual stage ratios, and it returns each stage ratio, the output speed and torque, noting that idler gears change only the direction of rotation, not the ratio. The solve endpoint finds the missing one of the input speed, the output speed and the ratio from the other two — for example, the ratio needed to drop a 1500 rpm motor to a 500 rpm output. Everything is computed locally and deterministically, so it is instant and private. Ideal for drivetrain, robotics and machine-design tools, gearbox and transmission selection, bicycle and vehicle gearing, and mechanical-engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is gear-train ratio and torque; for spur-gear tooth geometry use a spur-gear API.

#gear-ratio #gearbox #drivetrain #transmission #mechanical-engineering #developer-tools
api.oanor.com/gearratio-api
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/api/gearratio-api/openapi.json
/api/gearratio-api/llms.txt

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API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
86 ms
Server probes · 24h
Subscribers
3,511
active
Total calls
28
last 7 days
status Full status page → · 20 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 3,000 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • Single-pair gear ratio endpoint
  • Deterministic local compute, no upstream
  • JSON ratio + reduction output
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Starter

€8.00 /month

  • 40,000 calls / month
  • 5 requests / second
  • Hard cap (429 above quota, no overage)
  • Ratio, output speed and torque maths
  • Multi-stage gear-train chaining
  • Driver/driven tooth-count inputs
  • Email support
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Pro

€22.00 /month

  • 250,000 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • Full drivetrain & gearbox modelling
  • Compound and planetary gear stages
  • Batch ratio computation
  • Priority support
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Mega

€69.00 /month

  • 1,500,000 calls / month
  • 60 requests / second
  • Hard cap (429 above quota, no overage)
  • High-volume drivetrain simulation throughput
  • All gear-train, speed & torque endpoints
  • Bulk batch + highest rate limit
  • SLA-backed dedicated support
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Related APIs

Other APIs with overlapping tags.

Tire & Drivetrain API

Tyre, wheel and drivetrain maths as an API. The tire endpoint parses a metric tyre size such as 205/55R16 into all its real dimensions — section width, aspect ratio, sidewall height, rim and overall diameter in millimetres and inches, rolling circumference, and revolutions per kilometre and per mile. The compare endpoint takes an original and a replacement tyre size and works out the change in overall diameter and the resulting speedometer and odometer error — so you know how much faster you are really going than the dial shows after a tyre change. The gear endpoint computes a gear ratio from ring and pinion tooth counts, or the road speed from engine RPM, total gear ratio and tyre size. Everything is computed locally and deterministically, so it is instant and private. Ideal for automotive and motorsport apps, tyre shops and fitment tools, modding and restomod planning, and vehicle configurators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is tyre and drivetrain maths; for vehicle specifications by VIN use a vehicle-database API.

api.oanor.com/tirecalc-api

Clutch & Brake Torque API

Friction clutch and disc-brake torque as an API, computed locally and deterministically. The clutch endpoint computes the torque a plate (disc) clutch can transmit from the friction coefficient, the axial clamping force and the friction-face inner and outer radii, by both standard theories — uniform-wear, T = n·μ·F·(Ro+Ri)/2, and uniform-pressure, T = ⅔·n·μ·F·(Ro³−Ri³)/(Ro²−Ri²) — for any number of friction surfaces (a multi-plate clutch multiplies the torque), plus the maximum power at a given speed. The cone endpoint does the same for a cone clutch, T = n·μ·F·Rm/sin α, where the wedge angle amplifies the normal force by 1/sin α. The brake endpoint gives the braking torque of a disc brake, T = n·μ·F·R_eff, the power dissipated at a speed and — given a rotating inertia and its speed — the angular deceleration, the time and number of revolutions to stop, and the kinetic energy turned into heat. Everything is computed locally and deterministically, so it is instant and private. Ideal for drivetrain, automotive and machine-design tools, clutch, brake and winch engineering, and mechanical-engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is rotating-friction clutch and brake torque; for shaft torsion stress use a torsion API and for rope/belt capstan friction use a capstan API.

api.oanor.com/clutch-api

Shaft Torsion API

Shaft torsion as an API, computed locally and deterministically. The stress endpoint computes the maximum torsional shear stress in a circular shaft, τ = T·r/J — torque times the outer radius divided by the polar moment of inertia — for a solid shaft (J = π·d⁴/32) or a hollow tube (J = π·(D⁴−d⁴)/32), and solves the torque a shaft can carry for an allowable stress. The twist endpoint computes the angle of twist along the shaft, θ = T·L/(G·J), in radians and degrees, from the torque, length and the shear modulus (given directly or from a built-in material table — steel, aluminium, copper, titanium and more), plus the torsional stiffness G·J/L. The power endpoint relates the power a rotating shaft transmits to its torque and speed, P = T·ω = T·2πN/60, and solves any of the three, reporting power in watts, kilowatts and horsepower. Everything is computed locally and deterministically, so it is instant and private. Ideal for mechanical and drivetrain engineering tools, shaft, axle and coupling design, motor and gearbox apps, and machine-design education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is circular-shaft torsion; for axial stress-strain use a Young's-modulus API and for the 2D stress state use a Mohr-circle API.

api.oanor.com/torsion-api

Bicycle Gear API

Bicycle gearing maths as an API, computed locally and deterministically. The gear endpoint takes a chainring and cog tooth count and a wheel size and returns every common gearing metric: the gear ratio, gear inches (the classic measure — ratio times wheel diameter in inches), the gain ratio (Sheldon Brown's crank-length-aware measure), the development or rollout (metres travelled per crank revolution), and the road speed at a chosen cadence in km/h and mph. The speed endpoint converts between a gear-and-cadence and road speed in either direction — the speed at a cadence, or the cadence needed for a target speed. The table endpoint builds a gear chart: give one or more chainrings and a cassette of cogs and it returns a matrix of gear inches, development, gain ratio or ratio for every combination — ideal for visualising a drivetrain. Wheel size can be a preset (700x25c, 26-inch, 29er and more) or an exact rolling circumference in millimetres, and crank length is configurable for the gain ratio. Everything is computed locally and deterministically, so it is instant and private. Ideal for cycling apps and bike-fit tools, drivetrain and gear-ratio planners, and bike-shop and component sites. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is bicycle gearing; for cycling power, FTP and training zones use a cycling API.

api.oanor.com/bikegear-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Gear Ratio API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Gear Ratio API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Gear Ratio API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Gear Ratio API cost?
Gear Ratio API has a free tier with 100 calls / month. Paid plans start at €8.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Gear Ratio API GDPR-compliant?
All requests to Gear Ratio API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/gearratio-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/gearratio-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/gearratio-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/gearratio-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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